Technical Field
The present invention relates to a voltage level detecting device, a motor driving apparatus including the voltage level detecting device, a motor driving system including the voltage level detecting device, and a method for detecting a voltage level.
Description of the Related Art
There is a case where a mechanism is required for determining that continuous signals have reached a plurality of predetermined threshold voltage levels. For example, when a rotation position of a motor is controlled, such a mechanism determines that an input signal which changes according to a rotation phase of the motor has reached a threshold level provided for each predetermined phase, to detect a rotation phase of a rotor.
Specifically, as a method for detecting a rotation phase, one method is known in which a plurality of sensor signals (signals according to change of magnetic flux density) having a signal level according to the rotation position of the rotor of the motor is used to detect and output rotation phase information. In this method, the sensor signals are divided into a plurality of phase sections, and each divided sensor signal is compared with a threshold level provided for each predetermined phase, to detect that the sensor signal has reached the threshold level, thereby outputting a phase information signal indicating the detected phase.